The invention is particularly designed for kettles capable of accommodating a very large tire, or a plurality of smaller tires being repaired or retreaded, especially kettles in which a combination of steam and air, under pressure, are utilized in the heating and vulcanization of any vulcanizable material of the tire disposed within the kettle. Known prior art kettles have single inlets or several very widely spaced inlets through which the steam and air are admitted into the kettles. It is desirable to obtain a uniform mixture of air and steam within the chamber of the kettle to eliminate hot and cold spots within the kettle. Such spots have been tolerated in prior devices and overcome by rotating the tires within the kettle such that every portion of the tire passes through the same heat or temperature gradient, or by the use of blowers or fans to circulate the mixture of steam and air more evenly throughout the kettle. These systems have many disadvantages. For example, the rotation of large earthmover-type tires, can, in some cases, cause a breakdown of the bead areas of the tire. The invention is directed to the provision of a highly improved kettle and means for obtaining a uniform mixture of steam and air within the kettle.
Briefly stated, the invention is in a kettle used in the retreading and repair of tires. The kettle comprises a plurality of parts which, when brought together, form a chamber which is sealed from the ambient atmosphere. Means are provided for simultaneously circulating steam and air, under pressure, within the chamber when it is sealed. Such means include multiple inlets in the chamber for both the steam and air, the inlets of the steam being sufficiently close to those of the air to produce a more nearly uniform mixture of steam and air within the chamber.